What is a defining characteristic of cross-over study designs?

In a cross-over study design, a defining characteristic is that subjects receive both the treatment and the control in a sequential manner. This means that each participant serves as their own control, experiencing all interventions under investigation. This design is particularly useful for reducing variability because it allows for a direct comparison of the treatments within the same subjects, enhancing the study's sensitivity to changes due to the interventions.

This sequential treatment approach also minimizes the influences of confounding variables that might otherwise affect the outcomes between different groups. By alternating treatments, researchers can effectively isolate the impact of each treatment and enhance the reliability of the findings. In this way, cross-over designs can provide strong evidence of treatment effects relative to control conditions while controlling for individual differences among subjects.